Feb. 6, 2012 -- About half of elementary school students still have access to sugary snacks and other unhealthy options in school vending machines, according to a new study.

To combat rising childhood obesity rates, the Institute of Medicine recommended in 2007 that school meal programs be the primary source of nutrition in schools and called for limiting access to competitive foods in vending machines and other venues.

Despite these guidelines, researchers found that access to competitive foods did not change much in public or private elementary schools from 2006 to 2010.

More than half of elementary schools students, by 2010, could purchase foods from one or more sources in schools other than the school meal program, such as vending machines, school stores, or snack bars. Sugary foods were available to nearly all children with access to these options. Healthier options were less widely available.

"Because children spend many hours in school, changes are needed to make the school environment healthier by limiting the availability of less healthy food products," researcher Lindsey R. Turner, PhD, of the Institute for Health Research and Policy at the University of Illinois at Chicago, and colleagues write in Archives of Pediatric and Adolescent Medicine.

In 2010, the Healthy, Hunger-Free Kids Act gave the U.S. Department of Agriculture the authority to set nutritional standards for all foods sold in schools. Current regulations state that foods of minimal nutritional value cannot be sold in the cafeteria during lunchtime, but they may be sold in vending machines in schools at any time.

Access to Unhealthy Food Still Available

In the study, researchers surveyed more than 2,600 public elementary schools and about 1,200 private elementary schools concerning access to competitive food venues on school campuses each academic year from 2006 to 2010.

The results showed that access to competitive food venues and availability of most products did not change much over time.

By the 2009-2010 school year, about half of all public and private elementary school students had access to one or more competitive food venue. Nearly all of these venues still offered sugary foods, although candy was not widely available.

One exception was the availability of regular-fat ice cream products, which decreased over time. There was not a corresponding increase in the availability of low-fat ice cream products.

In fact, access to healthy options in competitive food venues was limited. Only about two-thirds of students with access were able to purchase salads, vegetables, or fruits in any competitive food venue.

Differences Between Schools

The survey also revealed several differences between different types of schools:

Students in suburban schools had more access to vending machines and other competitive food venues than students in urban schools (53% vs. 44%).

Suburban students were more likely to be able to purchase salty, low-fat, and sweet products in competitive venues.

Compared with public schools, private schools had more snack bars on campus with more access to candy and salty snacks.

In addition, researchers say there were important regional differences. Students in the South had more access to competitive food venues and salty and sweet products than those in other regions of the U.S.

"However, among public school students with access to competitive foods, those in the South also had greater availability of healthier foods compared with students in the Midwest or the West," write the researchers. "These results are intriguing considering that childhood obesity rates are highest in the South."

In an editorial that accompanies the study, experts say the results highlight that limiting access to competitive food venues in schools is only one of many strategies needed to fight childhood obesity.

"Competitive foods are often low in nutritional value and high in sugar, fat, and calories," writes Thomas N. Robinson, MD, MPH of Stanford University School of Medicine. "Their availability may increase stigmatization of and decrease participation in the school meal program, and they send mixed messages about healthful nutrition."